A sphere is unable to roll on

Step-by-step solution

For pure rolling, the velocity of the point of contact with the surface must be zero. On a smooth inclined surface, the component of gravity parallel to the incline causes a linear acceleration a = g . Since the surface is smooth, there is no frictional force. The normal reaction and gravitational force both pass through the center of mass, so the net torque about the center of mass is zero. Because the torque is zero, the angular acceleration is zero. The angular velocity remains constant while the linear velocity